Additives for the preparation of clear,impact resistant vinyl chloride polymer compositions

ABSTRACT

1. A CLEAR, IMPACT RESISTANT THERMOPLASTIC POLYMER COMPOSITION COMPRISING AN INITIMATE ADMIXTURE OF: (1) A POLYMER SUBSTRATE SELECTED FROM THE GROUP CONSISTING OF POLYVINYL CHLORIDE AD THE COPOLYMERS OF VINYL CHLORIDE WITH A MINOR PROPORTION OF AT LEAST ONE ETHYLENICALLY UNSATURATED COMONOMER AND (2) AN IMPACT ADDITIVE OF FROM 1 TO 35% BY WEIGHT, OF THE COMPOSITION, COMPRISING A COPOLYMER OF: (A) AT LEAST ONE C1-C12 ALKYL ACRYLATE ESTER AND (B) A SECOND M0ONOMER CONSISTING OF VINYLIDENE CHLORIDE, WHEREIN SAID IMPACT ADDITIVE COPOLYMER HAS A MONOMER RATIO OF ALKYL ACRYLATE ESTER TO VINYLIDENE CHLORIDE IN THE RANGE OF FROM ABOUT 35:65 TO 55:45 SO AS TO OBTAIN A COMPOSITION WHEREIN THE REFRACTIVE INDEX OF SAID IMPACT ADDITIVE IS ESSENTIALLY IDENTICAL TO THE REFRACTIVE INDEX OF SAID SUBSTRATE ADMIXED THEREWITH.

Oct. 8, 1974 R. GALLAGHER 5 ADDITIVES FOR THE PREPARATION OF CLEAR, IMPACT RESISTANT VINYL CHLORIDE POLYMER COPOSITIONS Original Filed April 15, 1970 2 Sheets-Sheet 1 BY WT., VINYLIDENE CHLORIDE 0 2O 4O 6O 80 I00 L540 D L535 INDEX REFRACTIVE (AT 23C.)

I00 80 6O 4O 2O 0 %BY WT., BUTYL ACRYLATE REFRACTIVE INDEX VS. COPOLYMER COMPOSITION FIG. I

APOLYBUTYL ACRYLATE BPOLYMETHYL METHACRYLATE C.POLYVINYL CHLORIDE D.(54=39=7) POLY(METHL METHACRYLATE=STYRENE= ACRYLONITRILE) E. (75 =25) POLY( STYRENE=ACRYLONITRILEI F. POLYV I NYLI DENE CHLORIDE Oct. 8, 1974 R. GALLAGHER 1 ADDITIVES FOR THE PREPARATION OF CLEAR, IMPACT RESISTANT VINYL CHLORIDE POLYMER COIPOSITIDNS Original Filed April 15, 1970 2 Sheets-Sheet 2 BY WT. BENZYL ACRYLATE BY WT., BUTYL ACRYLATE REFRACTIVE INDEX VS COPOLYMER COMPOSITION FIG. 2

A.POLYBUTYL ACRYLATE B. POLYME THY L METHACRYLATE C. POLYVINYL CHLORIDE D.(54=39=7) POLY(METHYL METHACRYLATE= STYRENE= ACRYLONITRILE) E. POLYBENZYL ACRYLATE United States Patent ADDITIVES FOR THE PREPARATION OF CLEAR,

IMPACT RESISTANT VINYL CHLORIDE POLY- MER COMPOSITIONS Ruth Gallagher, Dobbs Ferry, N.Y., assiguor to Stauffer Chemical Company, New York, N.Y.

Original application Apr. 15, E70, Ser. No. 28,897, now abandoned. Divided and this application Aug. 19, 1971, Ser. No. 165,803

Int. Cl. C08f 29/24 US. Cl. 260-899 24 Claims ABSTRACT OF THE DISCLOSURE Novel additives comprising copolymers of lower alkyl acrylates with either benzyl acrylate or vinylidene chloride are disclosed. It is further shown that these additives provide excellent results in the preparation of clear, impact resistant, thermoplastic compositions which comprise blends of the aforedescribed additives with a homoor copolymer of vinyl chloride.

RELATED APPLICATION This application is a division of application Ser. No. 28,897, filed Apr. 15, 1970, now abandoned.

Background of the Invention In order to improve their impact strength, it is a common practice to employ particles of rubber polymers to reinforce polyvinyl chloride (PVC), the various rigid copolymers of vinyl chloride as well as other hard, brittle thermoplastics such as polymethyl methacrylate, polystyrene, styrene-acrylonitrile copolymers and the like. As is known to those skilled in the art, the possession of a high degree of impact strength, i.e. the ability to withstand a rapidly applied shock, is an extremely desirable characteristic in any thermoplastic which is to be used for the preparation of cast or molded objects.

With respect to PVC and the rigid copolymers of vinyl chloride, the rubber additives most commonly utilized for the improvement of impact strength are the polyacrylates, polybutadiene and the copolymers of butadiene with acrylonitrile and/ or styrene. Unfortunately, the use of the latter types of impact additives does not provide completely satisfactory results. Thus, while polybutadiene and the butadiene copolymers yields blends with PVC or with vinyl chloride copolymers which display good impact strength and clarity, such blends are generally characterized by the fact that they become yellow during subsequent processing steps aud also by their poor, long term oxidative stability. On the other hand, the use of polyacrylate impact additives, yields compositions which have good stabiilty but which are, however, decidedly opaque.

It is, therefore, a prime object of this invention to provide a novel class of additives for use with the homoand copolymers of vinyl chloride which, when blended with the latter polymers, will yield compositions which while displaying high impact strength will also be characterized by their outstanding clarity, the absence of yellowing during processing and their excellent long term oxidative stability. Various other objects and advantages of this invention will be apparent from the disclosure which follows hereinafter.

TECHNICAL DISCLOSURE OF THE INVENTION It has now been discovered that the use, as impact additives for PVC and the rigid copolymers of vinyl cholride, of copolymers of the C -C alkyl esters of acrylic acid with either benzyl acrylate or vinylidene chloride yields high impact compositions of excellent clarity which do not 3,840,620 Patented Oct. 8, 1974 yellow during processing and which oxidative stability.

The novel impact additives ofthis invention comprise copolymers of: n 5.

(1) One or more C C alkyl acrylates including, for example, methyl, butyl,-isobutyl, n-hexyl, Z-ethylhexyl; 1noctyl, nonyl, decyl and lauryl acrylate with the usewof butyl acrylate being preferredgand (2) A second monomer selected from the group consisting of benzyl acrylate and vinylidene chloride. Also applicable are substituted benzyl acrylates, i.e. wherein the phenyl ring of the benzyl acrylate may be substituted with one or more lower alkyl, halo or nitrile groups.

It should be noted at this point, that the term copolymer, as used in this disclosure, is meant to encompass polymers derived from mixtures of two, three, or four or more monomers.

While the copolymers of some of the C -C alkyl acrylates are disclosed in the literature, they have not heretofore been suggested for use as impact additives for PVC and the rigid copolymers of vinyl chloride. However, the copolymers of the C -C alkyl acrylates with benzyl acrylate are believed to comprise new compositions of matter which are not, per se, disclosed in the literature.

The polymeric substrates with which these novel impact additives may be blended as part of the novel process of this invention include, as already been stated, PVC and the rigid copolymers of vinyl chloride. The latter rigid copolymers include, for example, copolymers containing a major proportion, by weight, of vinyl chloride together with one or more ethylenically unsaturated comonomers which may include, for example: vinyl esters of aliphatic and aromatic acids such as vinyl acetate, vinyl propionate and vinyl benzoate; vinylidene halides such as vinylidene chloride; C -C alkyl esters of acrylic and methacrylic acid such as the methyl, butyl, 2-ethylhexyl and lauryl esters of acrylic and methacrylic acids, the C -C monoaud dialkyl esters of ethylenically unsaturated dicarboxylic acids such as dibutyl fumarate and mono-methyl maleate; ethylenically unsaturated aromatic compounds such as styrene and alpha-methyl styrene; ethylenically unsaturated monoand discarboxylic acids, their amides, anhydrides, and nitriles such as acrylic, methacrylic, fumaric, maleic, itaconic, citraconic and aconitic acids; acrylonitrile, methacrylonitrile, acrylamide, methacrylamide, maleimide and maleic anhydride; and, C C alkyl vinyl ethers such as methyl vinyl ether and stearyl vinyl ether. The preparation of PVC and of the rigid copolymers of vinyl chloride may be accomplished by means of polymerization procedures well known to those skilled in the art such, for example, as the free radical initiated bulk, suspension, emulsion and solution polymerization techniques.

Particularly useful as a polymeric substrate for use in the process of this invention are copolymers of vinyl chloride with up to about 20%, by weight, of vinyl acetate. It should also be noted that the impact additives of this invention can, if desired, be successfully employed with a variety of rigid thermoplastic polymers other than the homoand copolymers of vinyl chloride. Thus, for example, these additives may be employedwith polymethacrylonitrile, polymethyl methacrylate, polystyrene, poly(styrene acrylonitrile), poly(methyl methacrylatestyrene-acrylonitrile), and poly(methyl methacrylate-ethyl acrylate) as well as any of the possible copolymers of acrylonitrile, methacrylom'trile, styrene, alpha methyl styrene, methyl methacrylate and ethyl acrylate.

The preparation of the novel impact additives of this invention may be conveniently accomplished by means of. emulsion polymerization procedures well known to those skilled in the art which may be of either the onestep or seeded type using conventional emulsifiers and have good long term trile, .maleimide and maleic anhydride; and, C -C alkyl vinyl -ethers such as methyl vinyl ether and stearyl vinyl ether.

water soluble, free-radical initiatingvcatalysts. Thus, the selected monomers may be emulsified in water containing an effective concentration, eg from about 0.05 to 5%,

.asbased on the total-weight, of the monomer charge, of

one or more anionic, non-ionic or cationic emulsifiers 'SUClL'zfOI example, as" the alkyl carboxylic acid salts, the

-monomer charge, of a peroxy type compound such, for

example, as hydrogen peroxide, ammonium, sodium or .potassium persulfate or a redox type catalyst, such as mixtures of a persulfate with alkali metal bisulfites, thiosulfates or hydrosulfites.

Polymerization is then initiated by heating the catalyzed, aqueous monomer emulsion to a temperature of from about 20l00 C. and maintaining it Within the latter range for a period of from about 0.05 to 20 hours. The resulting copolymer emulsion should preferably have a resin solids content in the range of from about to 50% by weight. The copolymer particles should have a particle size in the range of from about 0.03-2.0 microns with the larger particle sizes being attained by the use of seed polymerization procedures whereby the polymerization is conducted in the presence of a previously prepared emulsion containing particles of one of the above described copolymer additives.

The novel impact additive copolymers of this invention should be prepared so as to contain from about 5 to 99%, and preferably 30 to 70%, by weight, of one or more C -C alkyl acrylates and from about 5 to 99%, and preferably 30-70%, by weight, of benzyl acrylate and or vinylidene chloride. If desired, these polymeric impact additives may be prepared in crosslinked form by the inclusion, in the initial polymerization recipe, of a vinyl monomer containing at least two reactive vinyl groups such, for example, as butylene glycol dimethacrylate, ethylene glycol dimethacrylate, divinyl benzene, allyl methacrylate, allyl acrylate, divinyl oxyethyl ether and diallyl adipate. The moieties derived from these optional crosslinking monomers may be present in the impact additives of this invention in a concentration of from about 0.1 to 5.0%, by weight.

Other optional monomers which are non-crosslinking may also be used in preparing the impact additive copolymers of this invention as a replacement for part of either their benzyl acrylate or vinylidene chloride component. Thus, these copolymer additives may contain up to about 40%, by weight, of one or more monomers which may include for example: vinyl esters of aliphatic and aromatic acids such as vinyl acetate, vinyl propionate and vinyl benzoate; vinylidene halides such as vinylidene chloride; C -C alkyl esters of acrylic and methacrylic acid such as the methyl, butyl, 2-cthylhexyl and lauryl esters of acrylic and methacrylic acid; the C C monoand dialkyl esters of ethylenically unsaturated dicarboxylic acids such as dibutyl fumarate, monomethyl maleate, ethylenically unsaturated aromatic compounds such as styrene and alpha-methyl styrene; ethylenically unsaturated monoand dicarboxylic acids, their amides, nitriles and anhydrides such as acrylic methacrylic, fumaric,

maleic, itaconic, citraconic and aconitic acids, arylonimethacrylonitrile, acrylamide, methacrylamide,

the copolymer additive may be coagulated or spray dried so as to yield the additive in a dry, powdery solid form which can then simply be mill blended or otherwise admixed with the substrate polymer which should also be in the form of a dry powder. Or, if desired, the additive and the substrate may be admixed while each is in the form of an aqueous latex or suspension and the resulting mixture coagulated or spray dried so as to obtain a dry blend.

The blending operation may also be carried out by means of a procedure in which the PVC or vinyl chloride copolymer which comprises the substrate is itself polymerized by means of an aqueous emulsion procedure, as described hereinabove, while in the presence of an aqueous emulsion containing particles of one or more of the copolymer additives of this invention. Alternatively, the PVC or rigid vinyl chloride copolymer which comprises the substrate polymer can be polymerized by means of an aqueous suspension procedure, as Will be described hereinbelow, in the presence of an aqueous emulsion containing one or more of the copolymer additives of this invention. With either of these blending procedures involving a polymerization step, the resulting impact resistant composition will be in the form of discrete particles of an interpolymer having an essentially heterogeneous composition in which the vinyl chloride monoor copolymer substrate has been polymerized in and/or around the previously prepared impact additive copolymer particles.

As is known to those skilled in the art, suspension polymerization involves a process wherein one or more monomers are dispersed in a suspension medium, usually water, which is a non-solvent for both the monomer phase and the resulting polymer. The polymerization is then conducted, under agitation, in the presence of a suspending agent, such as talc, clay, polyvinyl, alcohol, gelatine, hydroxymethyl cellulose or carboxymethyl cellulose, and a monomer soluble catalyst such as azobisisobutyronitrile, lauroyl peroxide, benzoyl peroxide, or isopropyl peroxydicarbonate. The resulting polymer particles are of a relatively larger mass, as compared with the particles obtained from an emulsion polymerization procedure, and will tend to more rapidly separate out from the suspension.

With respect to proportions, the novel, high clarity, impact resistant composition resulting from the process of this invention, i.e. the blends comprising an intimate admixture of the selected impact additive copolymer and a PVC or rigid vinyl chloride copolymer substrate, should be prepared so that from about 1 to about 35% of their total weight may comprise one or more of the above described impact additive copolymers. Optimum results are apparently realized with compositions containing one or more of these additives in a concentration of from about 515%, by weight. The precise concentration of impact additive that is utilized will be largely dependent upon the physical properties that are desired in the resulting composition. Thus, the presence of a higher concentration of the additive will generally result in a composition having a greater degree of impact resistance. It may also be noted that if the product resulting from the blending or interpolymerization of the impact additive copolymer with PVC, a rigid vinyl chloride copolymer or some other thermoplastic polymer substrate containing more of the impact additive copolymer than is required, the blend or interpolymer may be diluted with an additional quantity of the substrate polymer in order to achieve any desired level of impact resistance.

The selection of a particular impact additive copolymer for use in preparing a PVC or rigid vinyl chloride copolymer blend will be governed by the refractive index of the PVC or rigid vinyl chloride copolymer substrate with which it is to be admixed. Thus, the clarity, and therefore the utility, of the resulting blend is for the most part dependent upon choosing a copolymer additive whose refractive index (R is essentially identical to the R of the PVC or rigid vinyl chloride copolymer substrate which is to be admixed therewith. For example, since PVC, at about 20 C., has a R; of from about 1.53-1.54], one

could use, for example, a butyl acrylatezvinylidene chloride (45:55) copolymer or a butyl acrylatezbenzyl acrylate (55:45) copolymer either of which has a R, of about 1.53. Or, one may employ any of the, other copolymer additives of this invention which may have a R; value close to 1.539 in order to obtain an impact resistant composition displaying a high degree of clarity. Therefore, as the difference between the R, value of the copolymer additive and the R, value of the PVC or of the vinyl chloride copolymer substrate is increased, the clarity of the resulting mixture will, in turn, be progressively decreased.

Accordingly, the practitioner in the art need merely determine the R, value of his polymeric substrate, using any of the commercially available refractometers, prior to selecting a particular copolymer additive for admixture therewith. Moreover, it is quite simple to prepare the copolymer additives of this invention so as to obtain prod- -indices of the copolymer additives of this invention and various polymeric substrates are demonstrated in the appended drawings. Thus, FIG. 1 is a graph illustrating: (1) the R; values of various polymer substrates as depicted on the vertical axis; (2) the percent, by weight, of butyl acrylate in a butyl acrylatezvinylidene chloride copolymer system on the'lower horizontal axis; and (3) the percent, by weight, of vinylidene chloride in the same copolymer system on the upper horizontal axis. FIG. 2, on the other hand, is a graph illustrating: (l) the R; values of various polymer substrates on the vertical axis; (2) the percent, by weight, of butyl acrylate in a butyl acrylatezbenzyl acrylate copolymer system on the lower horizontal axis; and (3) the percent, by weight, of benzyl acrylate in this same copolymer system on the upper horizontal axis.

Thus, the diagonal line in each of FIGS. 1 and 2, readily reveals the relationship between the composition of each copolymer system and its refractive index, i.e. it reveals the R, for every combination of the two comonomers within the copolymer system, thereby permitting the practitioner to select the precise copolymer composition whose refractive index is equivalent to that of the particular polymeric substrate with which it is to be blended or interpolymerized. In particular, FIG. 1 reveal that a butyl acrylate copolymer containing about 50% by weight, of vinylidene chloride will have a R; of about 1.53 and tical R; value. In general, for use with a PVC or a rigid vinyl chloride copolymer substrate, the impact additive copolymers of this invention may have. a monomer ratio in the range of from about 35:65 to :35 C -C alkyl acrylate esterzbenzyl acrylate or vinylidene chloride with one or more optional comonomers being able to replace a portion of the benzyl acrylate or vinylidene chloride content of the copolymer.

The high clarity, impact resistant compositions of this invention can be prepared so as to contain various optional additives which may include, for example, plasticizers such as the alkyl esters of phthalic, adipic and sebacic acids and aryl phosphate esters such, for example, as dioctyl phthalate, ditridecyl phthaiate and tricresyl phosphate, etc.; lubricants such as stearic acid or its metal salts, petroleum based waxes, mineral oils, polyethylene, etc.; and heat and light stabilizers such as CaZn stearate, basic lead compounds, tin compounds, epoxidized oils, phenyl salicylates, benzophenones and benzotriazoles, etc. For a more complete listing of plasticizers, lubricants, stabilizers and other functional additives, one may consult Polyvinyl Chloride by H. A. Sarvetnick published by Van Nostrand Reinhold Co., New York, N.Y., in 1969.

The high clarity, impact resistant polymeric compositions resulting from the admixture of one or more of the above described impact additive copolymers with PVC or a rigid vinyl chloride copolymer substrate may be utilized in any of the coating, impregnating and molding applications known to those skilled in the art. For example, these compositions may be used for preparing such diverse items as calendered films, blow molded bottles, extruded flat bed and blown films, extruded articles and tubing, etc., and in carrying out such processes as injection molding, fluidized bed coating, electrostatic powder spraying and rotational coating, etc.

The following examples will further illustrate the embodiment of the invention. In these examples, all parts given are by weight unless otherwise noted.

EXAMPLE I This example illustrates the preparation of a number of butyl acrylatezvinylidene chloride copolymer rubber impact additives, for use in the process of this invention.

The following table describes the ingredients present in a number of polymerization recipes each of which was polymerized by being introduced into one quart bottles which were capped, and heated at C. for a period of 4 /2 hours while being rotated at 20 r.p.m. Recipes Nos. 8 and 9, however, were heated for 9 hours at 7 8 C. while being rotated at 20 r.p.m. The resulting copolymer products were obtained as stable aqueous latices having a resin solids content of about 27%, by weight, wherein the copolymer particles had a particle size range of from about 0.2-0.3 microns.

INITIAL COMPOSITION OF POLYMERIZATION RECIPE 1 The monomer ratio of each copolymer in the Table is given in the sequence: butyl acrylate vinylidene chloride butylene glycol dimethacrylate styrene (styrene 15 present only in Nos. 6 and 9). I An anionic surfactant comprising the bis(tndecyl) ester 0! sodium sulfosuecime acid.

can, therefore, be used with PVC which has the identical R; value. 011 the other hand, FIG. 2 reveals that a copolymer of butyl acrylate with about 25%, by weight, of benzyl acrylate will have a R; of only about 1.49 and can be used with polymethyl methacrylate which has the iden- EXAMPLE II This example illustrates the preparation of a number of impact resistant PVC compositions which contained, respectively, the various copolymer additives Whose preparation is described in Example I, hereinabove. In this instance, the procedure utilized for the preparation of these compositions involved the polymerization of PVC in the presence of an aqueous latex of the previously prepared impact additive copolymer particles. The relationship between the clarity of these compositions and the monomer ratio of the particular impact additive copolymer utilized for their preparation is also shown, the monomer ratio being directly determinative of therefractive index of the copolymer.

The following table describes the ingredients of a number of suspension polymerization recipes each of which was introduced into one quart bottles which were capped and heated at 60 C. for a period of 9 hours while being rotated at 37 r.p.m. In each case, there was produced an aqueous suspension containing about 27%, by weight, of particles each of which comprised an intimate, essentially heterogeneous admixture of interpolymer of PVC and about 15%, as based on the total weight of each particle, of the particular copolymer additive in whose presence it had been polymerized. In these interpolymer particles, the vinyl chloride had been polymerized in and/or around the particles of the impact additive copolymer. These interpolymer particles were recovered from their respective suspensions on a Biichner funnel and then air dried.

In this table, the numbers assigned to the copolymer impact additives correspond to the number by which these additives were identified in the Table set forth in Example I hereinabove.

Initial composition of polymerization recipe Impact Impact 1% solu- Azobisadditive additive tion of ISO- Vinyl Recipe copolymer copolymethyl butyrochloride No. latex No. mer latex Water cellulose nitrile monomer The clarity of these interpolymer particles was evaluated by means of a procedure in which 3.0 parts of each respective interpolymer was mixed by hand for about 2-3 minutes with 6.5 parts of dioctyl phthalate and 0.1 parts of an alkyl tin thioglycollate stabilizer as sold by M & T Chemicals, Inc. under the trademark Thermolite 31. A thin layer of each of the resulting plastisol mixtures was then spread upon a petri dish. The thus coated dishes were thereupon heated in an oven set at 190 C. for a period of about 25-30 minutes. Upon being removed from the oven, the dried plastisol coatings contained within each dish were visually examined in order to evaluate their clarity. The results of these observations are set forth in the following table:

X The control comprised a sample of unmodified PVC which had been polymerized by means of the identical procedure described hereinabove with the exception that it was not conducted in the presence of an aqueous atex of an impact additive copolymer.

The results shown in the above table indicate that maximum clarity is achieved, with PVC as the substrate, using butyl acrylatezvinylidene chloride copolymer additives Clearer '8 which contain from about 55-60%, by weight,- of vinylidene chloride. It is also revealed that styrene can' be substituted for a portion of the vinylidene chloride content of the copolymer additive without any loss inclarity.

' EXAMPLE III This example illustrates the preparation of a clear, im; pact resistant PVC composition by means of the process of this invention.

Part 1.--Prepar ation of a 0.3 micron 55:43:2 vinylidene chloride/2-ethylhexyl acrylate butylene glycol dimethacrylate copolymer latex The following reactants were introduced into -a one quart bottle which was capped and heated for 3V. hours at 70 C. while being rotated at 20 r.p.m.

315 gms. H O

68 ml. of a 1% aqueous solution of the of sodium sulfosuccini c acid.

45 ml. of a 2% aqueous solution of potassium persulfate.

99 gms. of vinylidene chloride.

77 gms. 2-ethylhexyl acrylate.

3.6 gms. butylene glycol dimethacrylate.

bis (tridecyl) ester By means of this procedure a latex whose particles had a particle size of about 0.3 microns and which had a 25% resin solids content was obtained.

Part. 2.-Preparation of a 0.6 micron 55:43:2 vinyliden chloride/ethylhexyl acrylate/butylene glycol dimethacrylate copolymer latex The following reactants were introduced in a 1 quart bottle which was capped and heated for 3% hours at 70-75 C. while being rotated at 20 r.p.m.

73 gms. of the aqueous copolymer whose preparation was described in Part 1 hereinabove.

1.5 ml. of a 1% aqueous solution of the bis(tridecyl) ester of sodium sulfosuccinic acid.

318 gms. water.

39 ml. of 2% aqueous solution of potassium persulfate.

88 gms. vinylidene chloride.

69 gms. 2-ethylhexyl acrylate.

3.6 gms. butylene glycol dimethacrylate.

This procedure yielded a latex whose copolymer particles had a particle size of about 0.6 microns and a resin solids content of about 28%.

Part 3.Preparation of a PVC-(vinylidene chlorider2- ethylhexyl acrylatezbutylene glycol dimethacrylate) suspension-emulsion interpolymer.

The following reactants were introduced into a one quart bottle which was capped and heated for 8 hours at 60 C. while being rotated at 40 r.p.m.

54 gms. of the copolymer latex whose preparation was described in Part 2 hereinabove.

196 gms. water. i i

72 ml. of a 1 aqueous solution of methyl cellulose.

0.075 gms. of azobisisobutyronitrile.

100 gms. vinyl chloride.

her of the copolymer additives whose preparationwas described in Example Ias well as .of the PVC-additive interpolymer whose preparation was described in Part 3 of Example III. In each case, a comparison is provided in which the additive or interpolymer is dilated, i.e. physically admixed, with PVC.

In evaluating these additive copolymers and interpolymer products, they were either milled alone or first diluted with the indicated amount of a commercially available polyvinyl chloride resin. In either case, the milling was conducted on a two-roll mill operating at 350-360 F. for a period of three minutes. As stabilizers, each sample contained 3 phr. of Thermolite 31 and 0.5 phr. of calcium stearate. The following table describes the composition of the various samples which were evaluated as well as the results obtained.

monomer ratio being directly determinative of the refractive index of the copolymer.

The following table describes the ingredients of a number of suspension polymerization recipes each of which was introduced into one quart bottles which were capped and heated at 60 C. for a period of 9 hours while being rotated at 37 rpm. In each case, there was produced an aqueous suspension containing about 27%, by weight, of particles each of which comprised an intimate, essentially heterogeneous admixture or interpolymer of PVC and about 15%, as based on the total weight of each particle, of the particular copolymer additive in whose presence it had been polymerized. In these interpolymer particles, the vinyl chloride had been polymerized in and/ or Final concentration Percent of rubber Tensile Percent of PVC copolymer Tensile impact Appearance product used for additive or strength b strength of mi e Product being tested used dilution I interpolymer (p.s.i (it./lbs./in. product Unmodified PVC eontrol 100 8, 050 95 Clear. Commercially available additive 10 90 6, 800 117 Do. Copolymer No. 5 of Example I 100 15 5, 090 208 Do. Do 66 33 230 106 Do. Interpolymer of Example III, Part 3 100 6, 300 150 Do. Do 66 33 10 6, 900 133 Do.

I PVC having a relative viscosity of 0.11 as determined at 30 C. in a 1 gm. deciliter solution of cyclohexanone.

b As determined by means of ASTM Procedure D-1708.

The results shown in the above table indicate the improved impact strength inherent in the compositions resulting from the process of this invention when compared with unmodified PVC.

EXAMPLE V This example illustrates the preparation of a number of butyl acrylatezbeuzyl acrylate copolymer rubbers, i.e. impact additives, for use in the process of this invention.

The following table describes the ingredients present in a number of polymerization recipes each of which was polymerized by being introduced into 16 oz. bottles which were then purged with nitrogen for ten minutes. The bottles were then capped and heated at 70 C. for 3 hrs. while being rotated at 20 r.p.m. The resulting copolymer rubbers were obtained as stable aqueous latices having a resin solids content of about 27-29%, by weight, wherein the copolymer particles had a particle size of about 0.2-0.3 microns.

s As determined by means of ASTM Procedure D-1822. A methyl methacrylatezacrylonitrile:butadienezstyrene interpolymer sold as Kane Ace B-12 by the Kanegfauchi Chemical Company.

around the particles of the impact additive copolymer. These interpolymer particles were recovered from their respective suspensions on a Biichner funnel and then air dried.

Initial composition of polymerization recipe 1 In this table, the numbers assigned to the copolymer impact additives correspond to the number by which these additives were identified in the table set forth in Example V hereinabove.

Initial composition of polymerization recipe Emulsifier M1 30% Butylene Copolymer 1% aqueous gylcol composiaqueous H202 Butyl Benzyl dimeth- Recipe number tion X H20 solution 2 solution acrylate acrylate acrylate /60 134 41 3. 5 50 None 1 The monomer ratio of each copolymer in the table is given in the sequence: butyl acrylate benzylacrolate butylene glycol dimethacrylate except in No. 9 wherein no butylene glycol dimethacrylate is present.

2 An anionic surfactant comprising the bis(tr1decyl) ester of sodium suliosuccinic acid.

EXAMPLE VI The clarity of these interpolymer particles was evalu- This example illustrates the preparation of a number ated by means of a procedure in which 3.0 parts of each respective interpolymer was mixed by hand for about 2-3 minutes with 6.5 parts of dioctyl phthalate and 0.1 parts of an alkyl tin thioglycollate stabilizer as sold by M & T Chemicals, Inc. under the trademark Thermolite 31. A thin layer of each of the resulting plastisol mixtures was then spread upon a petri dish. The thus coated dishes were thereupon heated in an oven set at C. for a period of about 25-30 minutes. Upon being removed from the oven, the dried plastisol coatings contained within each dish were visually examined in order to evaluate their 311 clarity.- The. results of these observations are set forth in the following table: 7

. 1 The control comprised a sample of unmodified PVC which had been polymerized by means of the identical procedure described hereinabove with the exception that it was not conducted in the presence oi an aqueous latex of an impact additive copolymer.

The results shown in the above table indicate that maxirn'um clarity is achieved, with PVC as the substrate, using butyl acrylatezbenzyl acrylate copolymer additives which contain from about 50-65% by weight, of benzyl acrylate.

' ating the impact strength of the PVC containing the butyl acrylatezbenzyl acrylate copolymer rubber additive incorporated therein; the preparation of the latter product having been described in Example VI hereinabove.

In evaluating these additive copolymers and interpolymer products, they were either milled alone or first diluted with the indicated amount of a commercially available polyvinyl chloride resin. In either case, the milling was conducted on a two-roll mill operating at 350-360 F. for a period of three minutes. As stabilizers, each sample contained 3 phr. of Thermolite 31 and 0.5 phr. of calcium stearate. The following table describes the composition of the various samples which were evaluated as well as the results obtained.

Percent Tensile Percent PVC Final impact of used conc. of strength b product for di copolymer (ft./lbs./

Product being tested used lution additive in?) Unmodified PVC control 100 95 Impact additive copolymer N 0. 4 of Example V 66 33 121 This example illustrates the preparation of a clear, impact resistant composition comprising a blend of a vinyl chloridezvinyl acetate copolymer and one of the novel impact additive copolymers of this invention.

To 100 gms. of an 85:15 vinyl chloridezvinyl acetate copolymer having an intrinsic viscosity of 1.5 as determined in a 1% solution of cyclohexanone at 25 0., there Was added 37 gms. of the rubber copolymer latex from recipe No. 4 of Example I, hereinabove. The resin-latex mixture was air dried to remove the water whereupon the resulting product could be formed into PVC sheets having good clarity and impact strength.

EXAMPLE IX In another variaiton of the process of this invention, it

is possible to graft a methyl methacrylate homoorcopolymer, i.e. polymethyl methacrylate or a copolymer of methyl methacrylate witha minor proportion of one or more ethylenically unsaturated comonomers such as ethyl .acrylate, onto the previously polymerized particles of one 268 gms. of the copolymer latex from Recipe No. 5 of Example I hereinabove (75 gms. of rubber) 68 gms. of methyl methacrylate monomer 7 gms. of ethyl acrylate.

17 gms. of a 2% aqueous solution of K S O gms. water.

A latex having a resin solids content of 30%, by weight, was obtained which was then air dried so as to obtain a solid polymer product. When this polymer was added to PVC at a 10-20 phr. level it formed a clear blend with improved impact resistance.

Variations may be made in proportions, procedures and materials without departing from the scope of this invention as defined in the following claims.

What is claimed is:

1. A clear, impact resistant thermoplastic polymer composition comprising an intimate admixture of:

(1) a polymer substrate selected from the group consisting of polyvinyl chloride and the copolymers of vinyl chloride with a minor proportion of at least one ethylenically unsaturated comonomer and (2) an impact additive of from 1 to 35% by weight, of

the composition, comprising a copolymer of:

(a) at least one C C alkyl acrylate ester and (b) a second monomer consisting of vinylidene chloride, wherein said impact-additive copolymer has a monomer ratio of alkyl acrylate ester to vinylidene chloride in the range of from about 35:65 to 55:45 so as to obtain a composition wherein the refractive index of said impact additive is essentially identical to the refractive index of said substrate admixed therewith.

2. The composition of Claim 1, wherein said polymer substrate is a copolymer of vinyl chloride with a minor proportion of vinyl acetate.

3. The composition of Claim 1, wherein the C -C alkyl acrylate of said impact additive copolymer is butyl acrylate.

4. The composition of Claim 1, wherein said impact additive copolymer also contains at least one crosslinking comonomer having at least two reactive vinyl groups.

5. The composition of Claim 4, wherein said crosslinking comonomer is butylene glycol dimethacrylate.

6. The composition of Claim 1, wherein said impact additive copolymer contains at least one additional noncrosslinking comonomer.

7. The composition of Claim 1, wherein said polymer substrate is present in and/or around particles of said impact additive copolymer.

8. A method for the preparation of a clear, impact resistant, thermoplastic polymer composition, said method comprising the intimate admixture of:

(1) a polymer substrate selected from the group consisting of polyvinyl chloride and the copolymers of vinyl chloride with a minor proportion of at least one ethylenically unsaturated comonomer with (2) an impact additive of from 1 to 35% by weight, of

the composition, comprising a copolymer of:

(a) at least one C C alkyl acrylate ester and (b) a second monomer consisting of vinylidene chloride, wherein said impact additive copolymer has a monomer ratio of alkyl acrylate ester to vinylidene chloride in the range of from about 35:65 to 55:45 so as to obtain a composition wherein the refractive index of said impact additive is essentially identical to the refractive index of said substrate admixed therewith.

9. The method of Claim 8, wherein said polymer substrate is polyvinyl chloride.

10. The method of Claim 8, wherein said polymer substrate is a copolymer of vinyl chloride with a minor proportion of vinyl acetate.

11. The method of Claim 1, wherein the C C alkyl acrylate of said impact additive copolymer is butyl acrylate.

12. The method of Claim 8, wherein said impact additive copolymer also contains at least one crosslinking comonomer having at least two reactive vinyl groups.

13. The method of Claim 12, wherein said crosslinking comonomer is butylene glycol dimethacrylate.

14. The method of Claim 8, wherein said impact additive copolymer contains at least one additional non-crosslinking comonomer.

15. The method of Claim 8, wherein the intimate admixture of said polymer substrate with said impact additive copolymer is effected by polymerizing said polymer substrate in the presence of said impact additive copolymer.

16. The method of Claim 15, wherein said polymer substrate is suspension polymerized while in the presence of an aqueous emulsion containing particles of said impact additive copolymer.

17. The method of Claim 15, wherein said polymer substrate is emulsion polymerized while in the presence of 14 an aqueous emulsion containing particles of said impact additive copolymer.

18. The product resulting from the process of Claim 16.

19. The product resulting from the process of Claim 17.

20. The composition of Claim 1, wherein said impact additive copolymer exists in a concentration of from about 5 to 15% by weight.

21. The composition of Claim 1, wherein one or more optional additives selected from the group consisting of plasticizers, lubricants and stabilizers, are included.

22. The composition of Claim 1, wherein the refractive index is from about 1.53-1.54.

23. The composition of Claim 3, wherein said impact additive consists of a copolymer of butyl acrylate and vinylidene chloride, and contains from about to by weight, of vinylidene chloride.

24. The composition of Claim 23 wherein styrene is substituted for a portion of the vinylidene chloride.

References Cited UNITED STATES PATENTS 1/1972 De Witt et al 260878 R 7/1961 Protzman 260-885 US. Cl. X.R.

26023 AR, 31.8 M, 45.75 K, 80.81, 86.1 E, 86.3, 898, 901

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION PATENT NO. 1 3 40 20 DATED 3 October 8, 1974 Page 1 of 2 INVENTORtS) T Ruth Gallagher It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown'below:

Column 2, line 42, the term "discarboxylic should read dicarboxylic Column 3, line 20, the term "0.05" should read 9 0.25

Column 3, line 64, the term "aryloni" should read acryloni Column 6, line 17, the term "CaZn" should read Ca/Zn Column 6, line 37, the term "the" should read this In the tabulation bridging columns 5 and 6 entitled Initial Composition of Polymerization Recipe", the recitation in footnote 1 lacks a slash mark between "acrylate and vinyllidene", between "chloride" and "butylene", and between dimethacrylate" and "styrene". Thus, the terms should read acrylate/vinylidene chloride/butylene and dimethacrylate/styrene At Column 7, in the tabulation appearing after line 57,

in the 4th line of footnote 1, the term, "atex" should read latex Column 9, line 3, the term "dilated should read diluted UNETED STATES PATENT OFFICE CERTEFICATE 0F CGRRECTION O PATENT NO. 3,840,620

DATED October 1974 Page 2 of 2 lNVEN-wmsl 1 Ruth Gallagher It is certified that error appears in the above-identified patent and that said Letters Patent e are hereby corrected as shown below:

In the table bridging columns 9 and 10 at line 15, in footnote a, the term "0.11" should read a In the table at column 10, starting at line 33,

entitled "Initial Composition of Polymerization Recipe", in the 5th column from the left, entitled "1% solution of methylis cellulose", the term "methylis" should read methyl At column ll line 72, the term "variaiton" should read variation At column 13, in claim 11, the term "claim 1" should read Q claim 8 Signed and Sealed this eleventh Of May 1976 [SEAL] O Arrest:

ljUifH C. M A SON C. MARSHALL DANN Q msrrng ()jjrccr (ummissimu'r nj'lau'nts and Trademarks 

1. A CLEAR, IMPACT RESISTANT THERMOPLASTIC POLYMER COMPOSITION COMPRISING AN INITIMATE ADMIXTURE OF: (1) A POLYMER SUBSTRATE SELECTED FROM THE GROUP CONSISTING OF POLYVINYL CHLORIDE AD THE COPOLYMERS OF VINYL CHLORIDE WITH A MINOR PROPORTION OF AT LEAST ONE ETHYLENICALLY UNSATURATED COMONOMER AND (2) AN IMPACT ADDITIVE OF FROM 1 TO 35% BY WEIGHT, OF THE COMPOSITION, COMPRISING A COPOLYMER OF: (A) AT LEAST ONE C1-C12 ALKYL ACRYLATE ESTER AND (B) A SECOND M0ONOMER CONSISTING OF VINYLIDENE CHLORIDE, WHEREIN SAID IMPACT ADDITIVE COPOLYMER HAS A MONOMER RATIO OF ALKYL ACRYLATE ESTER TO VINYLIDENE CHLORIDE IN THE RANGE OF FROM ABOUT 35:65 TO 55:45 SO AS TO OBTAIN A COMPOSITION WHEREIN THE REFRACTIVE INDEX OF SAID IMPACT ADDITIVE IS ESSENTIALLY IDENTICAL TO THE REFRACTIVE INDEX OF SAID SUBSTRATE ADMIXED THEREWITH. 